An image forming apparatus such as a copying machine or a multifunction printer carries out image processing with respect to image data of a target image to be printed in accordance with a document type and setting conditions (printing density, percentage for an enlarging/reducing process, one-side printing or two-sided printing, margin size, and the like). Furthermore, there are some image forming apparatuses that display a preview of the target image to be printed on a display section of a display apparatus, on the basis of the image data that has been subjected to the image processing. There are various types of how to display a preview, for example, a display type in which the target image to be printed is displayed on the display section page by page, and a display type in which target images to be printed, made up of a plurality of pages, are displayed on the display section at once.
Furthermore, there are some image forming apparatuses having a function of changing a color of an image to be printed out, following a color setting selected by a user. In this case, the user sets a full-color mode, a monochrome mode, or the like mode as the color setting. However, in some cases, the user does not know whether a document is a color document or a monochrome document. In view of this, some image forming apparatuses have an auto color selection (ACS) function for automatically determining whether the document is a color document or a monochrome document. For example, Japanese Patent Application Publication, Tokukai, No. 2001-83759 A (Publication Date: Mar. 30, 2001) discloses an image forming apparatus that carries out an ACS process only when an auto color selection mode (ACS mode) is set. Further, Japanese Patent Application Publication, Tokukai, No. 2004-4622 A (Publication Date: Jan. 8, 2004) discloses an image forming apparatus that can designate a mode (standard mode) for use in image formation when a user does not clearly designate which mode is to be used for forming an image, an auto color selection mode, a full-color mode, or a black-and-white mode.
In some cases, after a user once sets a full-color mode or a monochrome mode and a document is subjected to a reading process, the user may want to change the color setting. For example, there may be a case where, after the reading process, the user finds that there are a few color pages being mixed in black-and-white pages in the document and the user may want to print the few color pages in the full-color mode. Further, in a case where the preview display is carried out, there may be a case where the user may want to change the color setting when the user checks a preview of an image.
However, with such conventional arrangements, in the cases where the user wants to change the color setting after the document has been subjected to the reading process, it is necessary that printing should be completed in the color setting that is initially set and then the document should be reset to be subjected to the reading process again. Further, in this case, pieces of paper used for the printing in the initially-set color setting are wasted.